Customer Reviews

Donny’s Unauthorized Technical Guide to Harley Davidson 1936-2008: Volume I: The Twin Cam

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Anyone that has been sucked into the Harley mystique and owns one of these expensive power mills owes it to themselves to read anything and everything by Harley Technical writer, Donny Petersen. Donny is the Jedi Master of Harley Davidson power trains. Donny's monthly tech articles for the extremely popular AMERICAN IRON magazine are indispensable guides for Modern Harley owners and mechanics. His articles are the primary reason I own a subscription to the magazine. I've learned a lot about Harleys from this man. His technical writing is brilliantly comprehensive to the expert and the layman. Donny is an invaluable teacher and second to none.

This volume contains articles about the Modern Twin Cams (1999 to the present). I suspect this series is going backwards in time if it is the first in a 12 volume set. What's covered in this volume is the introduction of the Twin Cam engine in late 1998, early Twin Cam problems, timing chest and gears, the history of Harley oil leaks, air flow problems, modifying Twin Cams into older frames, the clunky (my words) new 6 speed tranny, and the introduction of the 2007 96ci engine. My guess is that subsequent volumes will contain more indepth articles on the Twin Cam 88, 96, and 110 CVOs, while regressing to the earlier engine designs.

Here's hoping that Donny covers the entire gamut of Harley engine evolution going back to EVOs, Shovels, Panheads, and Knuckleheads. (Starting with the 1936 Knucklehead means there will be no coverage on the 1909-1936 Flathead.) Even though I don't own any of these older mills, I'll surely purchase every volume. Donny makes reading the history of Harley engine design fascinating, to say the least. And must own reading for owners of these older engine designs.

My only complaint with Donny is that I think he's a little too forgiving of the new '07 and '08 EPA induced Harley design. These closed loop engines run far too hot and lean for an air cooled motor. IMHO, unmodified engine longevity and performance has got to be a serious issue with the newer Harleys. Donny has touched on the future of the Twin Cam due to overwhelming EPA constraints and the possible death of the Harley air cooled mystique. It could spell the end of the Classic Harley Davidson look. (I know there are some bearded diehard enthusiasts that are frowning right now. Man, I feel your pain. I have a little tear in my eye too.) Things are changing. The future is the water cooled design of the Harley V-Rod. If you own an '07 or '08 Twin Cam, you owe it to yourself to do some online research into overheating, "parade mode", and the O2 sensors. As far as I know, Donny has not mentioned the "wideband" O2 sensors fix for reducing the lean condition of these motors in any of his tech articles for AMERICAN IRON. I could be wrong, having possibly missed it or skimmed over it. And an investment into an oil cooler is a must. I did some online research into this for two of my friends that own '07 TC96s. And I have to say, I'm just grateful that I own an '06 TC88.

Other than this minor quibble, this is the man to read when it comes to understanding Harley power trains. If waiting to buy 12 volumes of tech articles is a little daunting, a subscription to AMERICAN IRON is in order. If for no other reason than to get Donny Petersen's tech articles. (Sorry Genevieve, but AMERICAN IRON needs more swimsuit models posing with the customs. Just a suggestion, Chris.)

Thanks, Donny. Keep up the great work. I always look forward to reading your knowledgeable articles.

ENJOY.

This intuitive and concise explanation of the Twin cam engine is by far one of the easiest technical reads I have encountered.
Donny Petersens conveyance of physics, geometry and how they apply to basic principals of engine dynamics makes the understanding seem simple.
I am certain that all one needs to do is study this, and the successive volumes to be able to understand enough to troubleshoot any problems
with his or her twin cam engine! Knowledge is power.
I'll not digress and insult any female journalists, AIM magazine and ALL of it's contributing writers make it the premeir Motorcycle monthly.
Thanks again Donny for sharing!

I like to have multiple reference manuals on anything I work on, since what one author may neglect, another will cover. Also, many technical manuals assume their readers to already have previous knowledge and skills. I've been stymied in the past when I'd encounter a statement in a manual like "remove outer cover" and there I would sit, staring at the damn thing, wondering why I can't get the cover off after tugging and wiggling and looking around under and alongside for screws or something thats holding this damn thing on. Then I find, trail and error, push this side, lift opposite side, pops off like it's pressurized. Why the hell didn't it say that in the manual?

Hey, I've never touted myself as a mechanic, but I like to do as much as I can to save money and have the knowledge in case I'm out on the road with a busted bike.

Probably Mr. Petersen does not have that problem. I've no doubt Donny is an crackerjack mechanic on Harleys, but his book is poorly organized, horribly edited and I feel more than a bit cheated.

I found a duplicate sub chapter in the first section and actually flipped the pages back and forth a couple of times thinking the printer had inserted the same page twice. Nope, different page numbers, same text.

One of the first photos I saw was a the inside of an evo head next to a twin cam head. The twin cam head was just a black blob without detail since it had carbon buildup on it. Completely useless.

I was expecting more cookbook fixes, how-to's with photos and illustrations and exploded diagrams. What I got was a collection of stories about visits to the powers-that-be at Harley and motorcycle trips, jumbled up with engineering explanations that are too general for me to use. While it was kind of cool reading about the secret inner workings of HD, that's not why I got the book and there is page after page of it.

I'm just a guy with a 2003 wide glide that wants to work on it and since I don't wrench for a living, need quite a bit of help from manuals. Perhaps my second run through this book can yield some helpful hints, but honestly, I don't really hold much hope.

Can't really recommend this book, except as a curiosity.

This is a GREAT book if you are a Harley Enthusiast looking for a greater understanding of the engineering and basic mechanics behind the Harley Davidson Twin Cam.

As one reviewer has said there are some 1st edition publishing blunders within the book such as the repeated pages and duplicated statements. But you can tell it was written by a gear head for gear heads.

I love the Chapter on Donny's first viewing of the Twin Cam Engine. He goes over all of his thoughts and requirements of what he wanted to see and also goes over what Harley has done to improve the engine since its 2000 introduction to the public. After reading this book you will have a new appreciation of the FATHEAD.

I for one am looking forward to the next edition!

This book was very informative, Donny is very informative. I Purchased his second volume as will. I was impressed with the amount of info.

You will not get ANY performance info out of this book like the title might lead you to believe. If you want to know exactly how well the HD MoCo's executives revere the author, and read his "dumbed down" descriptions of how the Twin Cam compares and contrasts to previous engines, then this is the book for you. No doubt Donny Petersen has an unparalleled breadth and depth of Harley knowledge, but he doesn't share any useful mechanical experience with us in this book. This is the first book in a 12 volume series; I hope the future volumes are more focused and substantial. How to Build a Harley Davidson Torque Monster is a great Twin Cam performance guide, if that's what you're looking for.

This book has excellent info for the ones who have not kept up with all of the changes in the current "Twin Cam" harley engine. Very detailed and concise.

If you have a question regarding your machine and what you would like to do to improve it, but are not sure which direction to take, then this book is for you. I want to put new geared cams into the engine to replace the stock chain parts, but which one? Donny Peterson explains the reason for the design, the improvements and the pitfalls of certain mods. He also describes the different manufactures parts (including part numbers) and guides you through some basic decision you will need to consider before opting for the mod.

His vast knowledge of the power-plant is absolutely astonishing. I also enjoyed his writing style, which made for an enlightening and humorous read.

This is the most comprehensive technical guide you could want, and along side your Harley service manual, you should have all the information you would most likely ever need.

This book could have been written in 1/3 the space of print. It was extremely repetative and I found some of the information incorrect. I do not recommend this book to anyone looking for technical information on the twin cam engine. It is more of an overview of the twin cam design.

I found this book a great read, very informative and well explained so even a layman could understand. I've known Donny for 36 years and his knowledge of HD and ability to put it to paper is truly incredible. I would recommend this book to anyone wanting to do more than just change the oil on their bike, or would just like to know how things got to be as they are today. I was impressed enough to buy his other two books in the series and await further editions.